1. Field of the Invention
The present invention relates to a coordinate input indicator for indicating an arbitrary position on the coordinate input surface of a coordinate input apparatus and inputting the coordinates of the indicated position and, more particularly, to a coordinate input indicator for an optical coordinate input apparatus for inputting coordinates by detecting the coordinates of the irradiated position of a light spot irradiating the coordinate input surface, which indicator is used to indicate an arbitrary position on the coordinate input surface, irradiate the surface with a light spot, and input coordinates.
2. Description of the Related Art
An optical coordinate input apparatus is used in, e.g., a large-display system capable of inputting coordinates. In this case, an arbitrary position on a display screen serving as the coordinate input surface of the large display is indicated by a coordinate input indicator (to be referred to as an indicator) having a light-emitting element, and irradiated with a light spot emitted by the light-emitting element. The coordinates of the irradiated position are input to control an externally connected computer or handwrite characters, figures, and the like.
Known examples of this optical coordinate input apparatus are one for sensing a light spot on the coordinate input surface using a CCD area sensor or linear sensor, and calculating and outputting the coordinate values of the light spot position by image processing using barycentric coordinates or pattern matching, and one using a position detection element (analog device capable of obtaining an output voltage corresponding to a light spot position) called a PSD.
For example, Japanese Patent Publication No. 7-76902 discloses an apparatus for sensing a light spot of a parallel beam of visible light with a video camera to detect the coordinates of the light spot irradiated position, and at the same time transmitting/receiving control signals by infrared diffused light. Japanese Patent Laid-Open No. 6-274266 discloses an apparatus for detecting coordinates using a linear CCD sensor and special optical mask. U.S. Pat. No. 2,503,182 discloses the arrangement and output coordinate correction method of an apparatus using a PSD.
However, no references particularly prescribe the structure around the light-emitting element, e.g., LED or semiconductor laser of a light-emitting portion for emitting a light spot in the indicators of these conventional optical coordinate input apparatuses. The light-emitting element is exposed at the distal end of the indicator, and light from the light-emitting element directly irradiates the coordinate input surface without the mediacy of any member. When characters, figures, and the like are handwritten using the indicator as a so-called input pen, the light-emitting element is directly brought into contact with the coordinate input surface to input coordinates.
When the indicator is brought as an input pen into contact with the coordinate input surface to input coordinates, the transparent sealing resin of the light-emitting element, e.g., LED wears owing to friction against the coordinate input surface. The shape of the sealing resin serving as a lens changes to decrease the light irradiation amount from the LED or change the light distribution, resulting in low coordinate detection precision.
The light-emitting element such as an LED is an industrial general-purpose member. To improve the transparent sealing resin of the light-emitting element itself in order to reduce wear, the material must be improved in consideration of corrosion resistance against a light-emitting chip. Such light-emitting element requires a higher cost than a general-purpose member.
A light-emitting portion equipped with a filter has conventionally been proposed. However, the filter itself is an optical component which inhibits wear and scratches, and is part of a light-emitting element serving as a light-emitting member. No arrangement against wear and scratches is disclosed.
If the light-emitting element or filter greatly wears, the light-emitting element or filter must be exchanged, or the whole indicator must be exchanged.
If the wearing or scratched light-emitting element or filter is repetitively brought into contact with the coordinate input surface, it also scratches the coordinate input surface.
On the other hand, the indicator is often used as a large-size input device in combination with a large-size display device or singly for the purpose of presentation. The indicator is used in different modes, i.e., when the indicator is directly brought into contact with an input screen to indicate an arbitrary position as an input pen, and when the indicator remote-indicates an arbitrary position as a pointer. The indicator must change its light irradiation state so as to form optimal light spots in the respective modes.
The present invention has been made to overcome the conventional drawbacks, and has as its object to provide a coordinate input indicator which is used in an optical coordinate input apparatus, prevent a light-emitting element for emitting light to form a light spot from wearing and scratching, and attain high operability.
It is another object of the present invention to provide a coordinate input indicator capable of maintaining a stable emission state for a long time and inputting coordinates at high resolution and high precision.
To achieve the above objects, according to the present invention, there is provided a coordinate input indicator which forms a light spot on a coordinate input surface of an optical coordinate input apparatus to input coordinates, and has at a distal end a light-emitting element for forming a light spot, comprising:
a cap which is made of a transparent material and covers the light-emitting element at the distal end of the indicator,
wherein the cap contacts the coordinate input surface when the distal end of the indicator is brought into contact with the coordinate input surface to input coordinates.
In this arrangement, when the distal end of the indicator is brought into contact with the coordinate input surface to input coordinates, the cap contacts the coordinate input surface, but the light-emitting element does not contact the coordinate input surface. The light-emitting element can be prevented from being worn and scratched by the contact.
According to the present invention, the cap is spaced apart from the light-emitting element.
In this arrangement, when the distal end of the indicator is brought into contact with the coordinate input surface to input coordinates, no external force is applied to the light-emitting element. The light-emitting element can be prevented from being damaged by the external force.
According to the present invention, the cap is attached to a main body of the coordinate input indicator via an elastic cushioning member, and
the cap is attached to the light-emitting element via a transparent elastic cushioning member.
These arrangements can lessen shocks applied to the cap upon pressing the cap against the coordinate input surface to input coordinates.
According to the present invention, the transparent material forming the cap reduces a coefficient of friction on a surface of the cap,
grained slipping members mainly containing a lubricant for reducing the coefficient of friction of the cap are interspersed on at least a surface of the cap, and
linear slipping members mainly containing a lubricant for reducing the coefficient of friction of the cap are formed on a surface of the cap.
These arrangements can reduce the coefficient of friction on the cap surface. Particularly when characters, line drawings, and the like are input by moving the cap in contact with the coordinate input surface, the cap slips well. The cap and coordinate input surface can be prevented from being worn and scratched, and the operability of the indicator is improved.
To achieve the above objects, a coordinate input indicator according to the present invention comprises the following arrangement.
That is, a coordinate input indicator for irradiating a predetermined position on a coordinate input screen with light to form a light spot, and inputting coordinates corresponding to the light spot, comprises:
light-emitting means, incorporated in the indicator, for emitting light; and
a transparent member which covers the light-emitting means and is detachable from the indicator.
The transparent member is preferably made of at least one transparent resin material selected from the group consisting of PMMA (polymethyl methacrylate), AS (styrene-acrylonitrile copolymer), PS (polystyrene), PC (polycarbonate), and epoxy resin.
The transparent member preferably has an almost hemispherical dome-like shape with a predetermined thickness.
The transparent member preferably has a concave lens for diffusing light toward the coordinate input screen.
The transparent member preferably has a convex lens characteristic for condensing light on the coordinate input screen.
It is preferable that the transparent member comprise a first transparent member having a concave lens for diffusing light toward the coordinate input screen, and a second transparent member having a convex lens characteristic for condensing light on the coordinate input screen,
the first transparent member having an almost hemispherical dome-like shape,
the second transparent member having a cylindrical shape, and
the second transparent member be attached to the first transparent member attached to the light-emitting means.
It is preferable that the transparent member comprise at least a first transparent member having a concave lens for diffusing light toward the coordinate input screen, and a second transparent member having a convex lens characteristic for condensing light on the coordinate input screen, and
the first and second transparent members constitute zoom lens mechanism.
The transparent member preferably comprises a plurality of exchangeable transparent members having different optical irradiation characteristics.
To achieve the above objects, according to the resent invention, there is provided a coordinate input indicator of an optical coordinate input apparatus, comprising:
a light-emitting element (e.g., an LED or semiconductor laser) which is attached to a distal end of the coordinate input indicator to emit light in order to form a light spot;
a cap which is made of a transparent material (e.g., a transparent resin material), covers the light-emitting element, and is movably attached;
control means for controlling driving of the light-emitting element; and
switching means (tact switch) which operates interlockingly with the cap and switches driving control of the light-emitting element by the control means,
wherein the cap is pressed/separated against/from the coordinate input surface to operate the switching means, and driving control of the light-emitting element by the control means is switched.
In this arrangement, the light-emitting element is covered with the cap. When the coordinate input indicator is brought into contact with the coordinate input surface to input coordinates, the light-emitting element can be prevented from being worn and scratched by friction against the coordinate input surface.
Driving control of the light-emitting element is switched by pressing/separating the cap against/from the coordinate input surface. For example, the light-emitting element is driven by pressing the cap against the coordinate input surface, and driving of the light-emitting element is stopped by separating the cap from the coordinate input surface. Driving control of the light-emitting element need not be additionally switched, resulting in high operability.
The cap is movably spaced apart from the light-emitting element so as not to apply an external force to the light-emitting element upon pressing the cap against the coordinate input surface.
The indicator preferably further comprises means for adjusting an operating stroke or operating pressure by which the switching means operates interlockingly with the cap.
It is preferable that the cap be detachable from a main body of the coordinate input indicator, and the switching means not be operated when the cap is removed from the main body.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.